This invention relates primarily to scales, and more specifically, to a bearing mechanism for the support of a platform in a domestic scale.
The typical domestic platform scale includes two generally flat housing portions, one being a base and the other being a platform which is superimposed over the base and substantially coextensive therewith. The base includes a peripheral, upstanding flange which is received inside of a corresponding downwardly extending peripheral flange on the platform. The weighing mechanism is supported on the base in the area between the platform and the base.
The weighing mechanism typically includes a number of force collecting levers which are pivotally supported at one end in each of the corners of the base and have means for delivering a force to a spring, the deflection of which is measured to indicate the weigh applied to the platform. To transfer the weight or force produced by the weight on the platform to the force collecting levers, there are typically four bearing members in the corners of the platform which transfer force to the four levers mounted on the base. It is important that the forces be applied precisely to the pre-determined bearing points located on each of the four levers. In the past, this has required a multi-piece bearing, as shown in the U.S. Pat. No. to Hanson, No. 3,134,451. The approach disclosed in the Hanson patent involved a bearing post pivotally supporting a rocking member or link which could adjust in its engagement with the force collecting lever to avoid the introduction of any binding or twisting moments to the lever in transferring the downward force from the platform to the force collecting lever.
Several attempts have been made in the past to simplify this platform bearing structure, one being shown in U.S. Hanson, et al. Pat. No. 4,452,326 and another in the German Offenlegungsschrift 2,364,293. Both of these prior art patents teach the concept of having a one-piece bearing member which is loosely connected to the platform so that it may pivot or rock to adjust itself to proper engagement with the bearing portion on the force collection lever. The concept of having the one-piece bearing member pivot about a point on the platform prevents the application of a pure vertical force to the force collecting lever and increases the possibility that an undesired binding or force moment will be applied to the force collection lever.